Are there particular smells that always bring you joy? When you smell certain things, such as your mother’s perfume or your favorite meal, those smells can bring up pleasant memories. These are called odor-linked memories because the memories are brought on by smells (odors). The experience that odor-linked memories cause is called the Proust effect. This name came about because the author Marcel Proust wrote in his book, Swann’s Way, that the smell of a pastry he dipped in his tea brought on a rush of joy associated with his childhood. This claim made researchers curious to know whether there was a scientific explanation for Mr. Proust’s experience.

What Is the Connection Between Smells and Memory?

Olfaction is just a fancy word for our sense of smell. Even though the connection between olfaction and memory is rarely thought about [1], it is actually very important. Odor-linked memories can be extremely powerful. In the laboratory, researchers ask participants to smell different odors and see what sorts of memories come to mind. The researchers then ask follow-up questions about each memory, such as whether it is clear vs. fuzzy or emotional vs. boring. It turns out that olfactory cues (smells or odors) are more effective at triggering clear and emotional memories than visual cues, such as images or photographs [2]. In fact, older adults can remember much older memories with a smell than with pictures or words [3]. So, if Mr. Proust saw a picture of his favorite pastry and the tea that he dipped it in, he might not have had such a strong experience connecting him to his childhood memories.

Researchers can use brain scans called functional magnetic resonance imaging (fMRI) to measure brain activity while people perform mental tasks. Because fMRI looks at how the brain functions [4], it can help researchers see which parts of the brain are more (or less) involved while people remember the past in response to odors or pictures. Do odor-linked memories cause different brain activation than picture-linked memories? Yes! fMRI evidence shows that the areas of the brain that process emotions are more active when people have odor-linked memories than memories brought on by pictures (Figure 1) [5].

Years of research helped us to understand that the emotional processing areas in the brain—the same areas activated by odors—include the amygdala and the hippocampus, which are located in the temporal lobes (Figure 2). The temporal lobes are under your skull near your left and right temples. The hippocampus is a seahorse-shaped brain area that is involved with associative learning, which is learning that occurs when you connect two separate events together. Odor-linked memory relies on associative learning because we associate (or link) the odor that we smell with the time(s) in our lives when we previously smelled it. As you can see in Figure 2, the amygdala and the hippocampus are really close together, which makes it easy for us to learn and remember emotional memories.

How do smells get to the brain, though? After entering the nose and passing through the olfactory bulb (Figure 3), smell information is sent to the amygdala and hippocampus. Olfaction is the only sense that gets processed in this brain area. Therefore, smell is the sense most strongly linked to brain areas that are involved in emotion, learning, and memory. Thanks to fMRI scans, we now have evidence to explain why the smell of freshly cut grass takes us back to a previous summer in our memories, or why Mr. Proust so clearly remembered his childhood just from smelling a pastry. Smelling the grass or a pastry activates the brain areas responsible for emotions and memories!

Mental and Physical Benefits of Odor-Linked Memories

Odor-linked memories are special because they can do more than just transport us back to a different time in our lives. They can improve our health as well. It might seem surprising that our sense of smell can have such a positive impact on our well-being, but it is true! Researchers have found that odor-linked memories can actually be more positive than memories that are brought on by any other senses [1]. Pleasant memories put us in good moods, and being in a good mood helps to reduce stress. Stress can present itself in our bodies as inflammation (swelling, redness), which is a sign doctors look for in many different diseases [1]. Therefore, when odor-linked memories reduce our stress levels, we relax, and our physical health improves.

In addition to improving our physical health, odor-linked memories can improve our mental health. Mental health benefits of these memories include boosts to self-esteem, improved social interactions, and a sense of optimism (a sunny outlook). Odor-linked memories have also been shown to inspire self-confidence and motivation, and even to help adults quit smoking cigarettes! When smokers had pleasant odor-linked memories, they said that their cigarette cravings were reduced [1].

What Else Is There to Know?

Our lives are affected by the smells around us in big ways. We know that certain odors can actually improve our lives in the long run, by making us healthier. You can even use what you know about odors and memory to help you in school. Because we know that odor is so strongly linked to memory, if you smell the same odor when you study for and take a test, you have a better chance of remembering what you studied! For example, if you use peppermint lip balm while studying, you should put on that same lip balm before your test. The smell of peppermint can help you remember what you studied because of associative memory. Researchers proved this using the smell of chocolate [6]! Just be sure not to use the same lip balm smell for multiple classes, so your brain can remember the right class!

What we have discovered about odor-linked memories is important, but there is still so much more to learn. Because positive memories can help lower stress, they also help improve mood and can help people change unwanted behaviors, like smoking. This means that the effects of odor-linked memories could be used in therapy and counseling, to help improve people’s lives in both the short- and long-term. In conclusion, there are many effects of odor-linked memories, but we are not done studying all the ways they affect our lives just yet. It is a good thing Mr. Proust dipped that pastry into his tea…otherwise, we might not be aware of all of the positive impacts that odor-linked memories can have!

Glossary

Proust Effect: ↑ The experience that is brought on by memories that are odor-linked, or associated with smells

Olfaction: ↑ The sense of smell. The adjective form, olfactory, means related to the sense of smell.

Functional Magnetic Resonance Imaging (fMRI): ↑ A technique for measuring brain activity as people do mental tasks. fMRI can show which areas of the brain help process different types of thoughts.

Amygdala: ↑ (sounds like “uh-mig-duh-luh”) A part of the brain involved with processing emotional memories and experiences.

Hippocampus: ↑ A part of the brain involved with learning, especially associative learning.

Temporal Lobes: ↑ The parts of the brain that the hippocampus and amygdala are found in. This brain area is involved in processing emotions.

Associative Learning: ↑ Learning that occurs when you connect two separate events or things together. For example, linking the smell of coffee to spending time with your grandparent.

Olfactory Bulb: ↑ The part of the brain that receives information about smells.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.